Drinking water in France is largely contaminated by residues from a fungicide banned for several years, a sign of the persistence in the environment of traces of pesticides even long after their use has ended, according to an ANSES report published on Thursday 6 April.

The National Agency for Health Security (ANSES) has studied water withdrawals throughout the country, including overseas, in particular in search of 157 pesticides and their metabolites, i.e. components resulting from their degradation. "Of the 157 compounds sought, 89 have been quantified at least once in raw water and 77 in treated water," says ANSES.

One case in particular attracted the attention of experts: the metabolite of chlorothalonil R471811 - the most frequently found, "in more than one sample in two" - which leads to exceedances of the quality limit (0.1 μg/litre) "in more than one sample in three".

This metabolite is derived from the degradation in the environment of chlorothalonil, a fungicide banned in France since 2020. The French authorities had been alerted to its frequent presence in Swiss drinking water.

"These results attest that, depending on their properties, certain pesticide metabolites may remain present in the environment for several years after the ban on the active substance from which they are derived," concludes ANSES.

A grace period until May 2020

The European Commission had not renewed in 2019 the authorization of chlorothalonil, marketed by the German Syngenta, and the France had granted a grace period until May 2020 for the disposal of stocks of the product.

Brussels stressed that it was "impossible to establish at present that the presence of metabolites of chlorothalonil in groundwater will not have adverse effects on human health".

The Commission cited the conclusions of the European Food Safety Authority (EFSA), which considered that chlorothalonil "should be classified as carcinogenic category 1B", i.e. carcinogenic "puted".

ANSES had taken up this argument in a note last year, recalling that studies on chlorothalonil had identified "renal tumors in rats and mice".

The agency highlighted the "lack of data to prove that the metabolite chlorothalonil R471811 does not share the mode of action of the parent AS (active substance) resulting in renal tumors".

Contacted by AFP, the Professional Federation of Water Companies (FP2E), the Ministry of Ecological Transition and that of Agriculture had not reacted Thursday in the early afternoon.

These revelations come as the Minister of Agriculture, Marc Fesneau, wants to return to the procedure for banning another product, the agricultural herbicide S-metolachlor, not yet banned by the European Union.

ANSES announced on 15 February its intention to ban the main uses of this molecule, whose chemical derivatives have been detected beyond the authorized limits in groundwater.

"I will not be the minister who abandons strategic decisions for our food sovereignty at the sole discretion of an agency," said Agriculture Minister Marc Fesneau.

With AFP

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